South Africa's government declined to directly address reports that anti-apartheid icon Nelson Mandela was being treated at a different hospital than previously identified, raising questions about who was caring for the 94-year-old.

Mandela, admitted on Saturday, had been thought to have been at 1 Military Hospital near the capital, Pretoria, after Defence Minister Nosiviwe Mapisa-Nqakula said she visited the leader there on Monday.

But as local media suggested Mandela was not at that hospital on Thursday night, presidential spokesman Mac Maharaj issued a statement seeming to indicate the politician was not there.

''President Mandela is being treated at a Pretoria hospital as said from the first statement we issued,'' Maharaj said.

''We have refrained from disclosing the hospital in order to ensure privacy and also to allow doctors space to do their work of caring for [him] without interruptions or undue pressure.''

It was not immediately clear if Mandela had been moved or if he had been at a different facility during his entire six-day stay in hospital, his longest since 2001, when he underwent radiation therapy after being diagnosed with prostate cancer.

On Monday, addressing journalists after her visit, Mapisa-Nqakula said: ''We confirm that former President Mandela is in [the] hospital, 1 Military Hospital, and he's doing very, very well.''

Government officials could not be reached for comment on Thursday night.

South Africa's government has said Mandela, initially admitted for medical tests, was being treated for a lung infection. Mandela has a history of lung problems, after falling ill with tuberculosis in 1988 towards the end of his 27 years in prison before his release and being elected president. While doctors said at the time the disease caused no permanent damage to his lungs, medical experts say tuberculosis can cause problems years later for those infected.

Mandela had an acute respiratory infection in January 2011 and the chaos surrounding his stay at a public hospital led to the South African military taking charge of his care and the government controlling information about his health.

On Thursday, President Jacob Zuma honoured Mandela by unveiling a statue of him in the city of Bloemfontein, also called Mangaung, which next week hosts the governing African National Congress political party's convention. Mandela served as figurehead of the party while in prison, later becoming its leader and the nation's president.